Phased locked loops (PLLs) are commonly used in a large number of applications within the radio frequency technology. For example, PLLs can be used as frequency modulation (FM) demodulators and can form the basis of indirect frequency synthesizers. Additionally, the PLLs can be used for different types of variable frequency filters and a host of other special applications. A PLL is a control system that can generate an output signal having a phase related to the phase of the PLL input signal. There are several differing types of PLL including analog and digital PLLs, which generally include common electronic circuit blocks, such as a variable frequency oscillator and a phase detector. For both the analog PLL and digital PLL, there are blocks that generate switching current passing through a supply source. The switching current can cause supply ringing and fluctuation. On the other hand, the linearity of these blocks is very sensitive to supply voltage variation.